Dien ap thu cap may o B la
$U_{2B}=\frac{P}{Icos\phi }=120V$
Nhu vay dien ap so cap cua may B la
$U_{1B}=120.K_{b}=1200V$
Theo bao toan cong suat nen co cuong do dong so cap cua B la :
$I_{1B}=\frac{P}{U_{1B}}=80V$
Dien ap tren 2 dau dien tro $r=15$ noi tu A den B la
$U_{r}=I_{1B}.r=80.15=1200V$
Tu day co dien ap thu cap o may A la:
$U_{2A}=\sqrt{U^{2}_{r}+U^{2}_{1B}}=1200\sqrt{2}V$